Silver halide emulsions containing naphthol color couplers



United States Patent US. C]. 96-55 6 Claims ABSTRACT OF THE DISCLOSURE Photographic elements are described which comprise a light-sensitive silver halide emulsion and a color coupler for cyan having the formula:

The color couplers are stable to light and heat and do not influence the viscosity of a gelatin silver halide emulsion when incorporated therein.

wherein:

The present invention relates to the production of coloured photographic images by colour development. It relates more particularly to novel cyan-forming colour couplers and to light-sensitive silver halide emulsion materials containing them.

The colour couplers suitable for use in silver halide materials have to meet the following main requirements: they should be fast to diffusion and react quickly and as completely as possible on colour development, yielding a colour image that absorbs light in a desired spectral region and that possesses a fastness to light as Well as a stability against humidity and heat as high as possible, particularly when produced in a positive or reversal material.

In addition to these requirements, which particularly relate to the quality of the developed, photographic mate rial, the colour couplers should also meet requirements of technological nature, which are of importance when preparing and coating the silver halide emulsion, e.g. the addition of the colour coupler to the emulsion may not involve an increase of the viscosity of the light-sensitive emulsion beyond allowable limits and/ or it may not give rise to great changes in viscosity with time.

Subject to the foregoing requirements it is an object of the present invention to provide novel colour couplers for cyan of the naphthol type, by means of which on colour development with a primary aromatic amino developing agent cyan dyes in a high yield are produced. The said dyes are very stable to light and heat and possess a high transmittance for light of the blue and green regions of the visible spectrum. Moreover said colour couplers do not, as a practical matter, influence the viscosity of a gelatin silver halide emulsion, when incorporated therein.

More particularly the present invention provides colour Patented Jan. 6, 1970 couplers for cyan corresponding to the following general formula:

OH or;

CONE- wherein:

X represents a halogen atom e.g. a chlorine, bromine or fluorine atom, preferably a chlorine atom,

R represents an aliphatic radical comprising at least 5 and most 20 carbon atoms, preferably a linear aliphatic carbon chain having at least 10 carbon atoms Z represents a hydrogen atom or a substituent e.g. a halogen atom such as a chlorine atom, a bromine atom or a fluorine atom, a phenyl group, an alkyl group such as a methyl, t-butyl, t-octyl, an aralkyl group such as a benzyl group, an alkoxy group such as a methoxy group, or a substituted amino group such as a dimethyl amino group.

Colour couplers of the same kind as those according to the present invention, which correspond to the above general formula with the diflerence however that X represents a sulphonic acid group, are described in U .K. patent specification 914,507 filed May 25, 1961 by General Anilin & Film Corporation. The colour couplers according to this UK. patent specification, however, adversely affeet the viscosity of the emulsion and give rise to dyeimages which are less stable against light and heat than those according to the present invention.

Specific compounds falling within the scope of the above formula have the following structural formulae:

2) iii-CH3 OO-NH CONH Hz) u-CHa OO--NH O-(CHzhs-CHa CHs The colour couplers for cyan according to the present invention can be prepared by allowing to react the phenylester of a 1 hydroXy-4-halogen-Z-naphthoic acid with the appropriate aromatic amine. The requisite aniline with a long chain alkoxy group in ortho position can be obtained by methods known in the organic chemical art, and the detailed preparation of such aniline compounds is not deemed necessary since the preparation will not give rise to difliculties to a technician skilled in organic chemistry.

The colour couplers of the invention can be homogeneously incorporated into a hydrophilic colloid composition according to one technique by first dissolving them in an alkaline solution of a water-miscible organic solvent e.g. ethanol, which may be mixed to some extent with water, and according to other techniques by first dissolving them in an organic solvent as described e.g. in the published Dutch patent applications 5/ 16423 and 65/ 16424 both filed Dec. 16, 1965 by Gevaert-Agfa N.V., in the published Dutch patent application 66/00098 and 66/00099 both filed Jan. 5, 1966 by Gevaert-Agfa NV. and in the published Dutch patent application 66/ 00628 filed Jan. 18, 1966 by Gevaert-Agfa NV. and then mixing the solution obtained with the photographic emulsion. Further, they may also be homogeneously distributed through the photographic emulsion in a water-immiscible organic solvent e.g. according to a technique described in U.S. patent specification 2,304,940 filed by Leopold D. Mannes and Leopold Godowsky Jr., issue date Dec. 15, 1942.

They may also be added to the composition of a water-permeable non-light-sensitive layer, which is in direct contact with the light-sensitive silver halide emulsion layer, or they may be incorporated into a non-light-sensitive layer, which is separated from the light-sensitive layer by a water-permeable non-light-sensitive layer.

The silver halide emulsion usually contains colloids such as gelatin, poly(vinyl alcohol), colloidion or other suitable natural or synthetic colloids. The photographic emulsion may further contain usual ingredients such as hardeners, chemical sensitizing agents, optical sensitizing agents, plasticizers, development accelerators, stabilizing agents and wetting agents.

The non-migratory colour couplers for cyan described in the present invention are preferably incorporated in the red-sensitized silver halide emulsion layer of a positive or reversal photographic colour material. According -to a common procedure in the art, said silver halide emulsion is coated as the first colour coupler containing layer of a photographic multilayer colour material. Such photographic multilayer colour material usually comprises in the given sequence a support, a red-sensitized silver halide emulsion layer with a colour coupler for cyan, a green-sensitized silver halide emulsion layer with a colour coupler for magenta and a blue-sensitive silver halide emulsion layer with a colour coupler for yellow. The support of this multi-layer material may consist of paper, glass, cellulose nitrate, a cellulose ester such as cellulose triacetate, polyester, polystyrene or another synthetic or natural resin.

A yellow filter layer generally comprising colloidal silver dispersed in gelatin is usually provided between the silver halide emulsion layer containing a colour coupler for yellow and the green-sensitized silver halide emulsion layer.

In order to produce a photographic colour image, the exposed silver halide emulsion layer containing the colour coupler for cyan according to the present invention is developed preferably with an aromatic primary amino developing substance.

All colour developing agents capable of forming quinonimine dyes can be utilized as developers. Aromatic primary amino compounds such as p phenylenediamine and derivatives such as N,N diethyl p phenylenediamine, N,N diethyl N sulphomethyl-p-phenylenediamine and N,N diethyl N carboxymethyl-p-phenylenediamine are preferably used.

Comparative tests as described in the following example illustrate the improved fastness to light of dyes obtained by means of colour couplers according to the present invention.

EXAMPLE CONE- To portion S:

13 g. of a colour coupler prepared as described in the UK. Patent specification 939,030 filed Oct. 31, 1960 by Gevaert Photo-Producten N.V. having the structural formula:

O-(CHeM-CTH To portion T: 12 g. of colour coupler according to the present invention having the following structural formula:

CONH

I or

To portion U: 13.5 g. of a colour coupler according to the UK. patent specification 914,507 filed May 25, 1961 by General Anilin & Film Corporation having the following structural formula:

0 ONE- S O;Na. C II;

Before being coated the pH of the emulsions is adjusted to pH 6 and after addition of the required hardeners for the gelatin and distilled water to obtain 1 liter, each of the emulsion portions is coated onto a cellulose triacetate support in such a way that the emulsion layers obtained after drying all have the same thickness.

After having been exposed through a step wedge and developed with N,N-diethyl-p-phenylene diamine as developing agent, the light-sensitive materials R, S, T and U are examined as to their fastness to light in an apparatus known as Xenotest wherein the bleaching exposure is carried out by means of a Xenon arc lamp. The Xenotest apparatus is marketed by the firm Quarzlampen Gesellschaft m.b.h. Hanau, Germany.

In the following table are listed the respective percentage losses in maximum density after an exposure-time of 15 hours in said apparatus.

Percent decrease in maximum density after 15 hours exposure with 21 Xenon arc lamp wherein:

X represents a halogen atom,

R represents an aliphatic radical comprising at least 5 and at most 20 carbon atoms, and

Z represents a hydrogen atom or a substituent selected from the group consisting of halogen, alkyl, aralkyl, phenyl, alkoxy and alkyl substituted amino.

2. The photographic emulsion of claim 1 which includes a water-permeable colloid as a carrier for the silver halide grains.

3. The photographic emulsion of claim 1 wherein X is a chlorine atom.

4. A photographic multilayer color material containing in a red-sensitized silver halide emulsion layer a color coupler for cyan having the formula:

?H (')R o ONH- Q Z wherein:

X represents a halogen atom, R represents an aliphatic radical comprising at least 5 and at most 20 carbon atoms, and

Z represents a hydrogen atom or a substituent selected from the group consisting of halogen, alkyl, aralkyl, phenyl, alkoxy and alkyl substituted amino.

5. The photographic multilayer color material of claim 4 wherein X is a chlorine atom.

6. A method of producing a cyan colored photographic image in a photographic material containing a lightsensitive silver halide emulsion, which method comprises exposing said material to light and color developing it, by allowing to react a color coupler having the formula:

I -C ONH- I r z wherein: X represents a halogen atom,

References Cited UNITED STATES PATENTS 3,079,259 2/1963 Rauch et a1 96100 FOREIGN PATENTS 831,731 3/ 1960 Great Britain.

J. TRAVIS BROWN, Primary Examiner US. Cl. X.R. 9674, 100 

